Suatu fungsi F(x):ax+b jika F(2):-2 dan F(-3):13 maka hitunglah nilai dari F(4)+F(5). Adalah?

f(x)=ax+b

f(2)=2a+b=-2
f(-3)=-3a+b=13
eliminasi, f(2) - f(-3)

5a=-15
a=-3

2a+b=-2
2(-3)+b=-2
-6+b=-2
b=4

f(4) + f(5)
=( a(4)+b) + (a(5)+b)
= ((-3)4+4) + ((-3)5+4)
=-8-11
=-19

silahkan dikoreksi kalau salah hitung

f(x) = ax + b

bila f(2) = -2,
a(2) + b = -2
• 2a + b = -2

bila f(-3) = 13,
a(-3) + b = 13
• -3a + b = 13

SPLDV
2a + b = -2
-3a + b = 13
----------------- —
5a = -15
a = -15 : 5
a = -3

Substitusikan,
2a + b = -2
2(-3) + b = -2
-6 + b = -2
b = -2+6
b = 4

masukkan ke rumus fungsi asli,
f(x) = ax + b,
• f(x) = -3x + 4

a. f(4),
f(x) = -3x + 4
= -3(4) + 4
= -12 + 4
= -8

b. f(5),
f(x) = -3x + 4
= -3(5) + 4
= -15 + 4
= -11

jadi, f(4) + f(5) = -8 + (-11)
= -8-11
= -19